package network;

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient {
    private DatagramSocket socket = null;

    //Udp本身不保存对端的信息，就自己的代码中保存一下
    private String serverIp;
    private int serverPort;

    // 和服务器不同, 此处的构造方法是要指定访问的服务器的地址.
    public UdpEchoClient(String serverIp,int serverPort) throws SocketException {
        this.serverIp = serverIp;
        this.serverPort = serverPort;
        socket = new DatagramSocket();
    }

    public void start() throws IOException {
        Scanner scanner = new Scanner(System.in);
        while(true){
            //1.从控制台读取用户输入的内容
            System.out.println("请输入要发送的内容：");
            if (!scanner.hasNext()){
                break;
            }
            String request = scanner.next();
            //2.把请求发送给服务器，需要构造DatagramPacket对象
            //    构造过程中, 不光要构造载荷, 还要设置服务器的 IP 和端口号
            DatagramPacket requestPacket = new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(serverIp),serverPort);
            //3.发送数据报
            socket.send(requestPacket);
            //4.接收服务器的响应
            DatagramPacket responsePacket = new DatagramPacket(new byte[4096],4096);
            socket.receive(responsePacket);
            //5.从服务器读取的数据进行解析，打印出来
            String response = new String(responsePacket.getData(),0, responsePacket.getLength());
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
        UdpEchoClient client = new UdpEchoClient("127.0.0.1",9090);
        client.start();
    }
}
